Embodiments of the present invention as exemplarily described herein relate generally to apparatuses for adjusting the spot size of radiation pulses and to methods of adjusting the spot size of radiation pulses.
An analysis apparatuses such as a mass spectrometer can analyze the composition of a target material. Often, a sample of the target material is provided to an analysis apparatus in the form of an aerosol. A conventional aerosol producing apparatus can produce an aerosol by directing a radiation pulse having a fluence sufficient to ablate a portion of the target material. The ablated material is typically ejected from the bulk of the target material in the form of an aerosol plume.
It is often desirable to perform different types of compositional analyses of the target material using the analysis apparatus. Consequently, it can be desirable for the aerosol producing apparatus to produce individual plumes of aerosols containing different amounts of target material. For example, to perform a “bulk compositional analysis” of the target material, the aerosol plume should generally be produced from a relatively large area of the target material. Thus, the aerosol, producing apparatus produces an aerosol plume that is relatively large in size and that contains a relatively large amount of material removed from the target. Such a bulk compositional analysis can be helpful in providing information indicating the amount of an arbitrary component is present in the target material. However, to perform a “spatial compositional analysis” of the target material, the aerosol plume should generally be produced from a relatively small area of the target material. Thus, the aerosol producing apparatus produces an aerosol plume that is relatively small in size and that contains a relatively small amount of material removed from the target. Such a spatial compositional analysis can be helpful in providing information indicating how the amount of an arbitrary component changes at different locations (e.g., within a region of interest) in the target material.
Conventionally, aerosol producing apparatuses produce aerosol plumes of different sizes by using an aperture wheel having a diaphragm with a plurality of apertures of varying sizes defined therein to “crop” the spot size of a radiation pulse used to produce the aerosol plume. While dimensions of the apertures can be precisely defined within the aperture wheel, the number of apertures defined within the aperture wheel depends upon the size of the aperture wheel as well as other size limitations of the aerosol producing apparatus.